res/res_pjsip_sdp_rtp: Revert 425922

This patch for r425922 introduced a bug, wherein sending an INVITE request
with no SDP would cause Asterisk to not send an SDP Offer in the 200
OK. The current structure of res_pjsip_sdp_rtp is a bit hard to deal with
to fix this, as create_outgoing_sdp has no knowledge of whether or not it is
creating an SDP as a new Offer or an Answer. This is something of an oversight
in the callback definition, as the caller of it does have this information.


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@425944 f38db490-d61c-443f-a65b-d21fe96a405b